EPA Research Partner Support Story: Addressing 6PPD & 6PPD-quinone (6PPD-q)
Partner: Interstate Technology & Regulatory Council (ITRC)
Challenge: Addressing 6PPD & 6PPD-quinone (6PPD-q)
Resource: 6PPD & 6PPD-q Technical Document, Web-based Training
Project Period: 2023 – 2024
6PPD-quinone (6PPD-q) is a chemical derived from 6PPD, a widely used chemical antioxidant used in tire rubber to prevent degradation. In recent years, 6PPD-q has been identified as acutely toxic to coho salmon and other aquatic species, especially in stormwater runoff—raising serious environmental and regulatory concerns. Many states, tribes, territories, and localities are facing growing challenges in addressing the emerging environmental risks posed by 6PPD and 6PPD-q, particularly loss of aquatic species.
“The ITRC Tire Anti-Degradants (6PPD) Team was challenged with developing relevant and sustainable guidance for the rapidly emerging contaminants of concern, 6PPD and 6PPD-quinone. The team’s success was strengthened in the established ITRC-EPA partnership. The 6PPD Team brought together experts from state, federal, local, and tribal governments, the tire industry, and other interested partners to provide cutting edge knowledge that allowed for a guidance document that contained the best available research, facts about these chemicals, and solutions that were being explored." ‒ ITRC 6PPD Team Leads Kelly Grant, California Department of Toxic Substances Control and Tanya Williams, Washington State Department of Ecology
ITRC launched the interdisciplinary Tire Anti-Degradants (6PPD) Team in 2023. EPA expertise, leadership and assistance were critical to many aspects of the team’s efforts. The Team conducted extensive research and review of the current scientific literature and research and published the 6PPD& 6PPD-q Technical Document in September 2024. This document provides a comprehensive overview of the current science and regulatory landscape surrounding 6PPD and 6PPD-q, including occurrence, analytical methods, toxicity, fate and transport, and mitigation strategies. The document also includes summaries of state-led monitoring efforts, international perspectives, and emerging technologies to reduce environmental impact.
In 2024-2025, ITRC developed a web-based training course to accompany the document. The training has reached thousands of participants from local, tribal, state, and federal agencies, equipping them with the tools to recognize, assess, and manage 6PPD-q–related risks in their jurisdictions. The document and training are especially valuable for stormwater managers, regulators, and researchers looking to assess and respond to 6PPD-q contamination in urban runoff.